package com.atguigu.nio;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.Buffer;
import java.nio.ByteBuffer;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Arrays;

/**
 * @author: 叶子
 * @date: 2022/01/18 19:46
 * Scattering: 将数据写入到buffer时，可以采用buffer数组，依次写入 [分散]
 * Gathering: 从buffer读取数据时，可以采用buffer数组，依次读
 **/
public class ScatteringAndGatheringTest {
    public static void main(String[] args) throws IOException {
//        使用ServerSocketChannel和SocketChannel 网络
        ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();
        InetSocketAddress inetSocketAddress = new InetSocketAddress(7000);
//        绑定端口到socket并启动
        serverSocketChannel.socket().bind(inetSocketAddress);
//        创建buffer数组
        ByteBuffer[] byteBuffers = new ByteBuffer[2];
        byteBuffers[0] = ByteBuffer.allocate(5);
        byteBuffers[1] = ByteBuffer.allocate(3);
//        等待客户端连接(telnet)
        SocketChannel socketChannel = serverSocketChannel.accept();
//        循环读取
        int messageLength = 8;//从客户端接收8个字节
        while (true){
            int byteRead = 0;
            while (byteRead<messageLength){
                long l = socketChannel.read(byteBuffers);
                byteRead += l;//累计读取的字节数
                System.out.println("byteRead="+byteRead);
//               使用流打印，看看当前的这个buffer的position和limit
                Arrays.asList(byteBuffers).stream().map(byteBuffer -> "position="+ byteBuffer.position()
                        +",limit="+byteBuffer.limit()).forEach(System.out::println);
            }
//            将所有的buffer进行flip
            Arrays.asList(byteBuffers).forEach(byteBuffer -> byteBuffer.flip());
//            将数据读出，显示到客户端
            long byteWrite = 0;
            while (byteWrite<messageLength){
                long l = socketChannel.write(byteBuffers);
                byteWrite += l;
            }
            //将所有的buffer进行clear
            Arrays.asList(byteBuffers).forEach(byteBuffer -> byteBuffer.clear());
            System.out.println("byteRead="+byteRead+",byteWrite="+byteWrite+",messageLength="+messageLength);
        }
    }
}